The present invention relates to an electrical connector and, in particular, a zero insertion force, pin grid array socket.
Integrated circuits (ICs) have become the world's standard for electronic circuits. These range from basic transistor networks to complex memory, microprocessor and multi-chip module circuits. The common denominator to all such circuits is that they are produced en mass on a substrate such as silicon and then separated into individual units commonly known as chips. The majority of chips are then mounted in a carrier for subsequent incorporation into end products. The basic size, shape and construction of the carrier is commonly known as the package and many standard packages have emerged. Some examples are commonly known as DIP, SOJ, PLCC, QFP and PGA. Chip packages have developed to accommodate both circuit function, i.e., number and placement of leads, and assembly trends, i.e., through-board and surface mount solder assembly. While the majority of IC devices are hard soldered in place, several factors such as device availability, testing, upgrades, etc., have traditionally shown that there is a need to socket ICs regardless of their package. IC sockets are known in the art for receiving pin grid array (PGA) packages. Previous PGA sockets required a high insertion force. Such sockets resulted in lead damage due to the high insertion and withdrawal forces. Presently, IC packages have increasingly larger pin counts due to the continued miniaturization of the ICs. Such increased pin counts require zero insertion force (ZIF) sockets. For example, Intel, Inc. OverDrive.TM. Processor Sockets are known in the art. Generally, the contacts used in these sockets are referred to as normally closed contacts. Such ZIF PGA sockets are known in the art but include complex and expensive contact designs. Such contact designs are stressed greatly as the insertion forces increase. Also, such common contact designs have large plating areas which increase cost. Further, such socket designs do not provide for adequate cooling of the IC packages. Accordingly, there is desired a ZIF PGA socket design which overcomes the aforementioned shortcomings.